Thermal control is an important aspect of spacecraft design and operation. A principal objective of a spacecraft thermal-control subsystem is to maintain internal and external components within temperature ranges appropriate to their operation. Thermal control in spacecraft generally involves the collection, transfer, and rejection of waste heat from the onboard heat loads to the surrounding space environment. In the vacuum environment of space, the primary heat rejection mechanism is radiation.
Radiators and similar heat-rejection devices generally operate by transferring heat from a fluid to a surface for radiation away from the fluid. In conventional spacecraft designs, a thermal-control subsystem may transfer waste heat to external radiator surfaces where the heat is radiated to the surrounding space environment.
Operational safety and reliability are of prime importance in most spacecraft apparatus due to the often critical functions they support. Radiators operated in a space environment are often subjected to extreme thermal cycling, which poses heavy structural demands on the radiator subcomponents including the bonds formed between fluid tubes and thermal-surface components. In addition, it is important that radiators and similar heat-rejection devices address other risk factors including damage by micrometeoroid and orbital debris (MMOD) impacts.